package com.tinywind.admin.common.config.shiro.filter;

import com.tinywind.admin.common.base.BaseResult;
import com.tinywind.admin.common.utils.JsonTool;
import com.tinywind.admin.module.system.entity.SysUserInfo;
import org.apache.shiro.web.filter.AccessControlFilter;
import org.apache.shiro.cache.Cache;
import org.apache.shiro.cache.CacheManager;
import org.apache.shiro.session.Session;
import org.apache.shiro.session.mgt.DefaultSessionKey;
import org.apache.shiro.session.mgt.SessionManager;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.util.WebUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
import java.io.Serializable;
import java.util.Deque;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;

/**
 * @author liuxingyu01
 * @date 2021-04-29-12:54
 * @description 自定义过滤器，用于 并发用户控制
 **/
public class KickoutControlFilter extends AccessControlFilter {
    final static Logger logger = LoggerFactory.getLogger(KickoutControlFilter.class);

    /**
     * 踢出之前登录的/之后登录的用户 默认踢出之前登录的用户
     */
    private boolean kickoutAfter = false;
    /**
     * 同一个帐号最大会话数 默认1
     */
    private int maxSession = 1;

    private SessionManager sessionManager;
    private Cache<String, Deque<Serializable>> cache;


    public void setKickoutAfter(boolean kickoutAfter) {
        this.kickoutAfter = kickoutAfter;
    }

    public void setMaxSession(int maxSession) {
        this.maxSession = maxSession;
    }

    public void setSessionManager(SessionManager sessionManager) {
        this.sessionManager = sessionManager;
    }

    //设置Cache的key的前缀
    public void setCacheManager(CacheManager cacheManager) {
        this.cache = cacheManager.getCache("kickout_log");
    }

    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
        return false;
    }

    @Override
    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {
        Subject subject = getSubject(request, response);
        if (!subject.isAuthenticated() && !subject.isRemembered()) {
            //如果没有登录，直接进行之后的流程
            return true;
        }

        Session session = subject.getSession();
        SysUserInfo user = (SysUserInfo) subject.getPrincipal();
        String username = user.getAccount();
        Serializable sessionId = session.getId();

        //读取缓存   没有就存入
        Deque<Serializable> deque = cache.get(username);

        //如果此用户没有session队列，也就是还没有登录过，缓存中没有
        //就new一个空队列，不然deque对象为空，会报空指针
        if (deque == null) {
            deque = new LinkedList<>();
        }

        //如果队列里没有此sessionId，且用户没有被踢出；放入队列
        if (!deque.contains(sessionId) && session.getAttribute("kickout") == null) {
            //将sessionId存入队列
            deque.push(sessionId);
            //将用户的sessionId队列缓存
            cache.put(username, deque);
        }

        // 如果队列里的sessionId数超出最大会话数，开始踢人
        while (deque.size() > maxSession) {
            Serializable kickoutSessionId;
            if (kickoutAfter) { //如果踢出后者
                kickoutSessionId = deque.removeFirst();
                //踢出后再更新下缓存队列
                cache.put(username, deque);
            } else { //否则踢出前者
                kickoutSessionId = deque.removeLast();
                //踢出后再更新下缓存队列
                cache.put(username, deque);
            }
            try {
                //获取被踢出的sessionId的session对象
                Session kickoutSession = sessionManager.getSession(new DefaultSessionKey(kickoutSessionId));
                if (kickoutSession != null) {
                    //设置会话的kickout属性表示踢出了
                    kickoutSession.setAttribute("kickout", true);
                }
            } catch (Exception e) {//ignore exception
            }
        }

        //如果被踢出了，直接退出，重定向到踢出后的地址
        if (session.getAttribute("kickout") != null) {
            //会话被踢出了
            try {
                //退出登录
                subject.logout();
            } catch (Exception e) { //ignore
            }
            saveRequest(request);


            BaseResult baseResult = new BaseResult(BaseResult.CODE_KICKOUT, "此账号已在其他地方登录，请重新登录！", null);
            // 输出json串
            out(response, baseResult);

            return false;
        }
        return true;
    }

    private void out(ServletResponse response, BaseResult baseResult) {
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        PrintWriter out = null;
        try {
            httpServletResponse.setContentType("application/json;charset=UTF-8");
            out = httpServletResponse.getWriter();
            out.write(JsonTool.toJsonString(baseResult));
        } catch (Exception e) {
            logger.error("KickoutControlFilter.class 输出JSON异常，可以忽略。Exception = {e}", e);
        } finally {
            if (null != out) {
                out.close();
            }
        }
    }

}

